.TH std::iostream_category 3 "2024.06.10" "http://cppreference.com" "C++ Standard Libary"
.SH NAME
std::iostream_category \- std::iostream_category

.SH Synopsis
   Defined in header <ios>
   const std::error_category& iostream_category() noexcept;  \fI(since C++11)\fP

   Obtains a reference to the static error category object for iostream errors. The
   object is required to override the virtual function error_category::name() to return
   a pointer to the string "iostream". It is used to identify error codes provided in
   the exceptions of type std::ios_base::failure.

.SH Parameters

   \fI(none)\fP

.SH Return value

   A reference to the static object of unspecified runtime type, derived from
   std::error_category.

.SH Example


// Run this code

 #include <fstream>
 #include <iostream>

 int main()
 {
     std::ifstream f("doesn't exist");
     try
     {
         f.exceptions(f.failbit);
     }
     catch (const std::ios_base::failure& e)
     {
         std::cout << "Caught an ios_base::failure.\\n"
                   << "Error code: " << e.code().value()
                   << " (" << e.code().message() << ")\\n"
                   << "Error category: " << e.code().category().name() << '\\n';

     }
 }

.SH Possible output:

 Caught an ios_base::failure.
 Error code: 1 (unspecified iostream_category error)
 Error category: iostream

   Defect reports

   The following behavior-changing defect reports were applied retroactively to
   previously published C++ standards.

      DR    Applied to            Behavior as published            Correct behavior
   LWG 2087 C++11      iostream_category was not declared noexcept declared noexcept

.SH See also

   failure stream exception
           \fI(public member class of std::ios_base)\fP
   io_errc the IO stream error codes
   \fI(C++11)\fP \fI(enum)\fP
